Decorative vinyl floor coverings are commonly installed in residential dwellings in North America. Manufacturers of vinyl floor coverings include Armstrong World Industries (Lancaster, Pa.), Mannington (Salem, N.J.), Congoleum Corporation (Mercerville, N.J.), and Tarkett Incorporated (Whitehall, Pa.). Contemporary floor covering materials are described in U.S. Pat. No. 5,308,694. Although there are a number of elaborate vinyl floor covering construction designs, most are comprised of a three-layered structure. The bottom layer generally consists of a plasticized polymeric film, felt, or paper. The middle layer is the decorative portion and often consists of polyvinyl chloride along with plasticizing agents, dyes and/or pigments, stabilizers, and/or other components. In many cases this decorative layer has a cellular structure, which is achieved by decomposing a blowing agent, most commonly azodicarbonamide, during the manufacturing process. In some cases a colored design is gravure-printed on the topside of the middle layer. A discontinuous pattern of foam inhibitor can also be deposited on the topside of the middle layer in order to yield a highly textured floor covering. The upper layer is known as the “wear layer” and often consists of a plasticized polyvinyl chloride or polyurethane film.
Most types of vinyl floor covering are thin and very conformable. Thus, they must be installed directly over a smooth, flat substrate. Residential subfloors consisting of ¾ inch oriented strand board or plywood subfloor panels mounted over 2 inch×10 inch joists are frequently abused during the home building process, and have surfaces that are often too rough and irregular to be used as a vinyl floor covering substrate. It is common practice to install a thin, smooth panel, known as an “underlayment panel”, over the rough subfloor just prior to installation of the vinyl floor covering. Typical underlayment panels are sanded and comprised of plywood, particleboard, oriented strandboard, or cement/fiber board. Plywood underlayments that are commonly used in North America include those derived from lauan veneer and manufactured in Indonesia and Malaysia. A plywood underlayment, known as MULTIPLY, is composed of aspen veneer and is manufactured by Columbia Forest Products (Greensboro, N.C.). Another plywood underlayment, known as TECHPLY, is composed of Russian birch veneer and is distributed in North America by the Plywood & Doors Mfrs. Corporation (Union, N.J.). A ⅜ inch thick cement/fiber board, known as FIBERBOND, is sold as underlayment by the Louisiana-Pacific Corporation (Portland, Oreg.).
Most underlayment panels for vinyl floor covering are comprised of wood laminates or composites. Wood is known to contain an array of extractives. Some of these extractives are soluble in the plasticizers used in vinyl flooring. Unfortunately, the plasticizers in vinyl flooring are known to migrate into the wooden underlayment and can dissolve otherwise immobile colored compounds. Under conditions of elevated temperatures, the dissolved colored compounds can rapidly diffuse into the vinyl floor covering, where they can be visible as a stain. Homeowners cannot remove this type of stain. Resolution generally requires replacement of the vinyl floor covering.
It is common for decorative, felt-backed, vinyl flooring to be installed directly over wooden subfloors in a so-called factory-built home. Adhesives are not typically used to secure the vinyl to the subfloor. Instead, the vinyl is simply stapled along the perimeter of the floor and walls are then installed directly over these attachment points. Transition molding can be used at carpet/vinyl interfaces.
There are a number of methods that can be used to inhibit the vinyl stain formation process. One method is to utilize a wooden subfloor that is composed of wood that has a minimal content of colored compounds that are soluble in vinyl plasticizer. For instance, Weyerhaeuser oriented strandboard (OSB) production facilities that serve this market avoid the use of wood species such as elm, which is now known to contain 7-hydroxycadalenal, which is an intensely yellow, plasticizer-soluble compound. Unfortunately, virtually all wood contains some level of colored extractives and it is not commercially feasible to remove these extractives for the manufactured housing market. A second method is to discontinue the use of plasticizer in the decorative vinyl flooring. This is known to virtually eliminate the staining potential of the vinyl. Unfortunately, the plasticizer is required in order to produce the vinyl flooring and in order to impart flexibility and toughness to it. Alternatively, an additional layer, which resists the migration of plasticizer, can be incorporated into the vinyl flooring. Such products are commercially available and are known to be more resistant to bottom-up stain formation. Unfortunately, these same products are more expensive.
Another set of solutions to this problem is based on the utilization of a third material in the floor system that can be positioned between the wood subfloor and the vinyl flooring. Appropriate materials will have very low plasticizer permeance. Examples of such materials include sheet goods such as aluminum foil and nylon film. These sheet goods can be very effective at inhibiting stain formation. Unfortunately, they are relatively expensive and inconvenient. Another class of material that can be installed between the wood and the vinyl to inhibit stain formation are liquid coatings, such as KILZ or BULLSEYE SHELLAC. This class also includes Portland cement-based coatings, as well as coating formulations based on magnesium hydroxide or a copper morpholine complex. Liquid coatings have the advantage of being relatively low in cost and they are easily applied to discrete portions of the subfloor that will be overlaid with vinyl flooring. However, liquid coatings have the disadvantage of requiring a drying period subsequent to application and prior to vinyl flooring installation.
Therefore, a need exists for a liquid composition that effectively inhibits bottom-up stain formation in overlaid vinyl flooring that does not require a drying period subsequent to application and prior to vinyl flooring installation. The present invention seeks to fulfill this need and provides further related advantages.